This invention relates to lasers and more particularly to laser apparatus for producing a coherent light output at visible portions of the spectrum.
There is a need for a source of tunable coherent light at visible wavelengths, i.e., 4000-7500 A. Coherent light at these wavelengths is useful for such diverse applications as spectroscopy, electro-optical warfare, and as a general research tool. Prior art apparatus for generating tunable coherent light is the dye laser, examples of which are described in the book "Dye Lasers," Topics in Applied Physics, Volume 1, F. P. Schafer, editor, Springer-Verlag, New York, 1973. The principal disadvantage of the dye laser is the difficulty involved in tuning it over a substantial wavelength range. In order to change the output wavelength by more than about 400 A, it is necessary to change the dye in the laser. This is time consuming, inconvenient, and imposes other limits on the utility of the laser. In addition, dyes deteriorate with time and must be periodically replaced.
This invention is directed to a source of visible coherent light which overcomes these disadvantages.